I expect it's the one listed as "old_alpha inf-20100618" , inf for infdev and 20100618 is the date.
You should start a new profile in the launcher and set a new game directory, check the box "Allow the use of old "Alpha" versions..." and chose that as the version, then just play as usual.
And switch profiles when you want to change between that and the modern versions.
How do you play the June 18, 2010 version of Infdev? What version of it is in the launcher? (It's in the launcher, I checked the Minecraft Wiki)
I expect it's the one listed as "old_alpha inf-20100618" , inf for infdev and 20100618 is the date.
You should start a new profile in the launcher and set a new game directory, check the box "Allow the use of old "Alpha" versions..." and chose that as the version, then just play as usual.
And switch profiles when you want to change between that and the modern versions.
Just testing.
Thanks a lot! But my Minecraft crashes every time I try to use that version, what should I do?